By far more familiar to Polish-Americans than to Poles. Apparently, it was considered quite the delicacy in 19th century Poland, and immigrants to the US made it a popular and integral part of their cuisine, whereas it died out in Poland. I never encountered it at all during my twelve years in Poland, though, nor anyone who had ever eaten it. The only times I heard it mentioned was as a direct literary reference to Pan Tadeusz.
Superb if cooked well. One of the culinary high points of Polish American cuisine. Truly awful if not (noodles or macaroni???????). Haven't had it in years, though, since my grandmothers died. Suspect it has mostly died out here, too.
As for "secret ingredients" that give soups in today's Poland their characteristic flavor, completely unfamiliar to Polish Americans, they are Vegeta, an flavor enhancer imported originally from Yugoslavia, Maggi, "European soy sauce" originally imported from Switzerland,and Knorr bullion cubes, a German invention. All three contain MSG. And, of course, salt. A lot of it. I never touched a salt-shaker during my stay in Poland, nor had any reason to.